Containers of various shapes, sizes and configurations have been employed to accommodate all manner of storage and transportation. Typically, in the case of containers primarily utilized to transport items, it is often necessary to protect these items from impact and/or environmental damage, as well as to make the container suitable for stacking and storage during transportation. These cases are generally manufactured through a rotational molding process, which offers impact resistant protection, strength, and watertight packaging.
To facilitate stacking, containers may include outer surfaces having structural profiles or stacking patterns. Such patterns allow other like containers to be stacked with one another during transport. The stacking patterns utilize complementary patterns on opposing sides of the container, oftentimes being mirror images of each other. For example, a stacking pattern may include a lid featuring a series of parallel ribs. The base may, in turn, have a series of protrusions that fit between the ribs allowing the base of a first container to be securely stacked on a lid of a second container.
In many applications, it is also desirable to be able to removably secure an accessory to a container. As will be appreciated, the type of accessory to be attached will vary depending upon the application. Regardless of the type of accessory, it is desirable that the accessory can be conveniently and securely attached in a variety of potential locations. It is also desirable that, once an accessory is removed, the container may be stacked upon another like container without the removal of the attachment mechanism.
To accomplish this, it has been found that with containers that include ribs in their stacking pattern, such as on the container lid, attachment devices that can receive and hold accessories may be secured between adjacent ribs, provided the ribs include a secure attachment location therefore. It has been further determined that a preferred attachment location for the secure and varied placement of such an attachment device is a series of undercut slots formed in a side surface of a rib.
Molding a stacking pattern with a series of undercut slots is not without its challenges. As stated, such containers are preferably rotomolded by melting powdered plastic in a mold. Forming the undercut slots is potentially problematic in that the undercuts may prevent removal of the container from the molding tool.
With the forgoing problems and concerns in mind, it is the general object of the present invention to provide a convenient method of molding containers to form a series of undercut slots allowing attachment of devices for holding accessories to a container.